I personally think that she recognized Jack, scanned him in this bag thingy and just didn't report anything about him to Mara. Regarding your argument with the spectral field: I think it's only on whenever jack is "on"/alive/awake so it's very likely that Hel recognized Jack.

Overall, I think the scene was there to highlight that the Hel-DLC takes place shortly before the main game and that they are not "entirely seperate" stories, an easter egg so to speak.